Ferengi coin

A Ferengi coin

A coin is a flat, usually disc-shaped piece of metal, which is or has been used as a form of currency among some cultures, such as the Ferengi and Humans.

Some types of coin include:

While cleaning up his bar, Quark found three coins on the floor of the second level and shouted angrily to Broik and another Ferengi waiter that they should leave because of their carelessness. (DS9: "The Passenger")

In 2368, when two different groups wished two use the thermal imaging array on the USS Enterprise-D, Lieutenant commander Data brought the problem to Lieutenant commander Geordi La Forge, who replied "Well, tell them to flip a coin", a reference to the practice of making a determination by which side of the coin was facing upwards when it landed. Data took La Forge literally and replied that he would replicate one. (TNG: "The Game")

In 2369, Nog paid with two coins for a jumja stick on Deep Space 9's Promenade. (DS9: "A Man Alone")

That same year, Quark narrowly avoided an assassination attempt as Grand Nagus by bending over to pick up a coin dropped on the floor of his bar. (DS9: "The Nagus")

It is unknown if that coin was a modern, latinum-based coin or simply an antique.